National experience with the implementation of predictive medicine in oncology: Example of Her-2/neu (c-erbB-2) gene.

Konference: 2009 5. sympózium a workshop molekulární patologie a histo-cyto-chemie

Kategorie: Onkologická diagnostika

Téma: The role of the pathologist in the indication of the cancer treatment

Číslo abstraktu: 007

Autoři: doc. MUDr. Marián Hajdúch, Ph.D.; RNDr. Radek Trojanec, Ph.D.; prof. MUDr. Zdeněk Kolář, CSc.; MUDr. Vladimíra Koudeláková (Palková); Mgr. Jitka Berkovcová, Ph.D.; RNDr. Božena Braunerová; MUDr. Kateřina Bouchalová (Špačková), Ph.D.; Doc. MUDr. Martin Tichý, CSc.; Mgr. Veronika Krejčí; prof. MUDr. Bohuslav Melichar, Ph.D.; MUDr. Karel Cwiertka, Ph.D.

Determination of Her-2/neu status is crucial for the effective indication of trastuzumab (Herceptin®) treatment. In the Czech Republic, Her-2/neu status is evaluated by FISH and immunohis-tochemistry at six Reference Centres (Laboratories of Predictive Medicine). However, some samples cannot be evaluated by FISH due to DNA degradation and those tumors were evaluated by quantitative real-time PCR for Her-2/ neu gene. Moreover, due to polysomy of chromosome 17 (OH17) at least 5-7 % of patients are not indicated for trastuzumab treatment as they do not fulfill the criteria of an Her-2/neu: CH17 ratio > 2.2. The efficacy of trastuzumab in polysomic patients has not yet been confirmed. In the Czech Republic, such patients are indicated for trastuzumab treatment only when they are immunohistochemically positive (3+).

More than 2818 breast cancer samples were evaluated in our institution over a period of seven years. Overall, 148 (5.25 %) cases failed to be concluded by FISH. Absence of cancer cells and/or DNA degradation in the tumor biopsy were the major causes of the failure. For such cases, quantitative real-time PCR comparing the Her-2/ neu gene status to reference genes dck, gcs1 and epn2 was established. Among 148 cases which failed using FISH technique, we have successfully investigated 77 patient samples by qRT-PCR achieving unambiguous results in 78 % (60/77).

In 13.8 % (368/2670) cases, polysomy of C17 was detected by centro-meric probe (CEP17). Using locus specific probe mapping of 17p11.2 region, we found that 57 % (212/368) of such a" polysomic cases" contain only 2 copies of CH17. We found in some instances, I the hybridization of centromeric probe was not specific enough and the probe also hybridized to centromeres of other chromosomes or the cells showed complex cytogenetic rearrangements which misrepresent the number of CH17.

Supported by grants MSM6198959216 and LC07017. Special thanks go to all cooperating departments, and health insurance companies.

Datum přednesení příspěvku: 24. 4. 2009